To go back to the OP's question - he wants to be fucked by a TS girl but wonders if the thought of it is better than the reality.
It's a tricky one to answer. It depends how skilful, patient and considerate the TS girl is. You can practise with butt plugs as much as you like but the first time someones puts a real, live cock up against your arsehole and starts to push, you will tense up and tighten up, as sure as night follows day. And if the person on the end of the cock (whether it's a TS girl or a TV/bloke) keeps pushing it's going to start hurting. And if the cock is really big, the pain will be excruciating. If this turns out to be your first taste of reality, it's self-evident that the thought was much, much better than the reality.
But it doesn't have to be like that. I have also been fucked by all possible variants of a cock owner and much like screwing female escorts, sometimes it's been very enjoyable, occasionally it's been a bit painful and unpleasant. But with one person, a TV, it's been sublime, one of the most enjoyable sexual experiences of my long and chequered career. And this TV's cock is longer and thicker than any of the others I've had up me; it's enormous. We've done it together several times and I've never experienced even a flicker of pain. Size isn't the problem; it's how it's done that matters.
The fucker has to overcome the natural butt clenching by the fuckee which I referred to earlier. This is done by very gentle massage and stimulation by fingers and or tongue of the anal area. It may take several minutes but in the end, the fuckee will start to lose his fear and relax. Gradually he will begin to find the massage of his arsehole pleasurable rather than threatening. At this point the tip of a finger can be inserted. Once the fuckee has relaxed again (he'll probably tense up when the finger first goes in) more finger can go in. When relaxation has again been achieved, you progress to two, then three fingers. When the fuckee is relaxed and genuinely enjoying this, the cock will go in with complete ease and no drama because the arsehole is so relaxed that it's gaping. Remember that with anal, the length of the cock is immaterial. Once it's comfortably in there's no difference between a six incher and a twelve incher. It's not like fucking a cunt where there is a limited amount of space to accommodate a cock. The first time my TV friend fucked me, it probably took twenty minutes of gentle preparation before the cock was introduced. Once it was in and I was filled with this monster, the pleasure was simply exquisite. I get hard just thinking about it. In this case, the reality was far better than any thoughts I had had about it beforehand.
So my advice would be, if you want to do it, do it. But make sure you do it with someone who knows what they're doing and who is willing to take the time and trouble to prepare you properly.
Hope this helps.